Fake implementation of winterop.dll.

If I compile this to Linux native code, and then run WiX under Mono,
it loads this library and gets past the first CabExtract call, so I
can find out what the next problem turns out to be.

fake-winterop.c

@@ -0,0 +1,153 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdarg.h>
+#include <string.h>
+#include <uchar.h>
+#include <err.h>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static char *ascii(const char16_t *wstr, bool translate_slashes)
+{
+    size_t len = 0;
+    for (const char16_t *wp = wstr; *wp; wp++)
+        len++;
+    char *ret = malloc(len + 1);
+    char *p = ret;
+    for (const char16_t *wp = wstr; *wp; wp++)
+        *p++ = (*wp == '\\' && translate_slashes ? '/' :
+                *wp < 0x80 ? *wp :
+                '?');
+    *p = '\0';
+    return ret;
+}
+
+static void system_argv(const char *cmd, ...)
+{
+    int nargs, nchars;
+    const char *word;
+    va_list ap;
+
+    va_start(ap, cmd);
+    nargs = 1;                         /* terminating NULL */
+    nchars = 0;
+    for (word = cmd; word; word = va_arg(ap, const char *)) {
+        nargs++;
+        nchars += 1 + strlen(word);
+    }
+    va_end(ap);
+
+    char *args[nargs], chars[nchars];
+    char **argp = args, *charp = chars;
+    va_start(ap, cmd);
+    for (word = cmd; word; word = va_arg(ap, const char *)) {
+        *argp++ = charp;
+        strcpy(charp, word);
+        charp += 1 + strlen(word);
+    }
+    va_end(ap);
+    *argp++ = NULL;
+
+    pid_t pid = fork();
+    if (pid < 0)
+        err(1, "fork");
+
+    if (pid == 0) {
+        execvp(args[0], args);
+        warn("execvp");
+        _exit(127);
+    }
+
+    int status;
+    if (waitpid(pid, &status, 0) != pid)
+        err(1, "waitpid");
+    if (!(WIFEXITED(status) && WEXITSTATUS(status) == 0))
+        errx(1, "subcommand failed");
+}
+
+uint32_t HashPublicKeyInfo(void *pCertContext,
+                           void *rgbSubjectKeyIdentifier,
+                           uint32_t *pcbSubjectKeyIndentifier)
+{
+    errx(1, "HashPublicKeyInfo NYI");
+}
+
+uint32_t ResetAcls(const char16_t **pwzFiles, uint32_t cFiles)
+{
+    return 0;
+}
+
+uint32_t CreateCabBegin(const char16_t *wzCab, const char16_t *wzCabDir,
+                        uint32_t dwMaxFiles, uint32_t dwMaxSize,
+                        uint32_t dwMaxThresh, int compression,
+                        void **out_ctx)
+{
+    fprintf(stderr, "CreateCabBegin(\"%s\", \"%s\", ...)!\n",
+            ascii(wzCab, true), ascii(wzCabDir, true));
+    return 0;
+}
+
+uint32_t CreateCabAddFile(const char16_t *wzFile, const char16_t *wzToken,
+                          void *pmfHash, void *ctx)
+{
+    fprintf(stderr, "CreateCabAddFile!\n");
+    return 0;
+}
+
+uint32_t CreateCabAddFiles(const char16_t *const *pwzFiles,
+                           const char16_t *const *pwzTokens,
+                           void *pmfHash, uint32_t cFiles, void *hContext)
+{
+    fprintf(stderr, "CreateCabAddFiles!\n");
+    return 0;
+}
+
+uint32_t CreateCabFinish(void *hContext, void *newCabNamesCallBackAddress)
+{
+    /* FIXME: newCabNamesCallBackAddress is actually a fn ptr of some kind */
+    fprintf(stderr, "CabCFinish(%p,%p)!\n",
+            hContext, newCabNamesCallBackAddress);
+    return 0;
+}
+
+void CreateCabCancel(void *hContext)
+{
+    fprintf(stderr, "CabCCancel(%p)!\n", hContext);
+}
+
+uint32_t ExtractCabBegin(void)
+{
+    return 0;
+}
+
+uint32_t ExtractCab(const char16_t *wzCabinet, const char16_t *wzExtractDir)
+{
+    char *cab = ascii(wzCabinet, true), *dir = ascii(wzExtractDir, true);
+    fprintf(stderr, "ExtractCab(\"%s\", \"%s\"\n", cab, dir);
+    system_argv("cabextract", "-d", dir, cab, (const char *)NULL);
+    return 0;
+}
+
+void ExtractCabFinish(void)
+{
+}
+
+uint32_t EnumerateCabBegin(void)
+{
+    return 0;
+}
+
+uint32_t EnumerateCab(const char16_t *wzCabinet, void *pfnNotify)
+{
+    /* FIXME: fpnNotify looks like a fn ptr again */
+    fprintf(stderr, "EnumerateCab!\n");
+    return 0;
+}
+
+void EnumerateCabFinish(void)
+{
+}

libwinterop.so.la

@@ -0,0 +1,42 @@
+# libsane-u12.la - a libtool library file
+# Generated by libtool (GNU libtool) 2.4.2
+#
+# Please DO NOT delete this file!
+# It is necessary for linking the library.
+
+# The name that we can dlopen(3).
+dlname='libwinterop.so'
+
+# Names of this library.
+library_names='libwinterop.so'
+
+# The name of the static archive.
+old_library='libwinterop.a'
+
+# Linker flags that can not go in dependency_libs.
+inherited_linker_flags=''
+
+# Libraries that this one depends upon.
+dependency_libs=''
+
+# Names of additional weak libraries provided by this library
+weak_library_names=''
+
+# Version information for libwinterop.
+current=1
+age=0
+revision=0
+
+# Is this an already installed library?
+installed=no
+
+# Should we warn about portability when linking against -modules?
+shouldnotlink=no
+
+# Files to dlopen/dlpreopen
+dlopen=''
+dlpreopen=''
+
+# Directory that this library needs to be installed in:
+libdir='/usr/lib/x86_64-linux-gnu'
+